Document feeding apparatus

ABSTRACT

Document feeding apparatus has provision for supporting a stack of documents above and spaced away from a vacuum feeding drum. A suction shoe is interposed between the stack and the drum and has a depression in that face nearer to the stack. The leading edge of the lowermost document of the stack is attracted into the depression so that it is separated from the stack and a knife is moved into the gap between the attracted edge and the stack to maintain the separation. The suction shoe is then withdrawn to allow the separated edge to move into contact with the vacuum drum which then withdraws the lowermost document completely from the stack. A refinement allows the thickness of document in the depression of the vacuum shoe to be examined in order to detect the separation of more than one document or to detect failure of a document to be separated before the feeding cycle is proceeded with.

United States Patent Derc' et a1.

[ 51 June 13, 1972 DOCUMENT FEEDING APPARATUS [72] Inventors: Roman Derc, Letchworth; Ronald John Frank Eitel, wel y Cecil Bragg Congleton, all of England [73] Assignee: International Computers Limited, London,

England [22] Filed: Sept. 3, 1970 [21 App]. No.: 69,200

[30] Foreign Application Priority Data Sept. 5, 1969 Great Britain ..44,026/69 [52] US. Cl. ..271/29, 271/32 [51 Int. (1 B6$h 3/50 [58] Field of Search ..271/29, 32, 20

[56] References Cited UNITED STATES PATENTS 3,494,61 1 2/1970 Richards ..271/29 3,371,331 2/1968 Buckholz... ..271/32 X 3,172,655 3/1965 Lenk ..271/29 X 7 1,286,153 11/1918 Tucker ..271/29 Primary Examiner-Joseph Wegbreit Attorney-Keith Misegades and George R. Douglas, Jr.

[571 Answer Document feeding apparatus has provision for supporting a stack of documents above and spaced away from a vacuum feeding drum. A suction shoe is interposed between the stack and the drum and has a depression in that face nearer to the stack. The leading edge of the lowermost document of the stack is attracted into the depression so that it is separated from the stack and a knife is moved into the gap between the attracted edge and the stack to maintain the separation. The suction shoe is then withdrawn to allow the separated edge to move into contact with the vacuum drum which then withdraws the lowermost document completely from the stack.

A refinement allows the thickness of document in the depression of the vacuum shoe tobe examined in order to detect the 5 Claims, 2 Drawing Figures CONTROL UNIT PATEHTEDJun 13 \972 sUcTmN SOURCE 4 BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to document feeding apparatus for feeding documents from a stack.

2. Description of the Prior Art Document feeding apparatus using a vacuum drum positioned adjacent but spaced away from a feeding face of a document stack has previously been proposed. Frequently such apparatus has required additional devices such as moveable suction cups to be moved over complex paths in order to pick up a document from the face of the stack and present it to the vacuum drum. Movement of such suction cups in this way often requires relatively complex mechanical linkages to control the path over which the cups are moved. In other cases knife feeds are used to ensure that only a single document is fed out of the stack towards the drum and such feeds are not entirely satisfactory in the case of flimsy documents which may be damaged by impact of feeding knives.

The present apparatus avoids the use of impacting knives in first separating an edge of a document from the stack and maintaining it in a separated position. The separated edge is then allowed to move from this position to the feeding drum simply by the retraction of the initial separating device. Thus the use of complex mechanical movements to control suction cups is also avoided, the only mechanical movements being obtained by permitting separating devices simply to pivot about a fixed axis.

SUMMARY OF THE INVENTION According to the present invention document feeding apparatus includes means for supporting a stack of documents; document feeding means adjacent one end face of the stack and spaced away from that document at said one end face; separator means operable to separate a portion of said document from the remainder of the stack and to retain the separated portion in a position intermediate the remainder of the stack and the document feeding means; and selectively operable means acting on the separator means to permit the separated portion of the document to move into feeding engagement with the feeding member to feed said document away from the stack. The separator means may include means for checking that the separated portion is a portion of only a single document.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic view of a document feeding apparatus. FIG. 2 is a sectional view through the apparatus of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings document feeding apparatus includes a table 2 arranged to support a stack 1 of documents. The document stack 1 is arranged on the table 2 with the leading edges of the documents aligned against a front wall 3. A vacuum feed drum 4 is positioned with its periphery slightly below the upper surface of the table 2. The leading edges of the documents in the stack I extend beyond the table 2 and therefore are not supported by the table 2. However, in a static condition of the feeding apparatus the leading edges of the documents are supported by a knife 5 and a suction shoe 6 so that the lowermost document is maintained spaced from the periphery of the feed drum 4.

The suction shoe 6 is formed with a concave depression 25 in its upper surface and a duct 7 extending through the shoe connects through a number of apertures 26 with the concave upper surface. The shoe 6 is mounted on an arm 8 pivoted about a shaft 9. The arm 8 is urged in an anti-clock-wise direction by a spring 10 so that the depression 25 in the shoe 6 i normally underlies and is spaced away from the leading edge of the lowermost document of the stack. The shoe 6 may be retracted to a position clear of the leading edge of the document by operation of an electromagnet 11 which attracts a bar 12 of magnetic material carried on the arm and causes the arm 8 to pivot in a clock-wise direction about the shaft 9. Similarly the knife 5 is mounted on a further arm 13 pivoted about the shaft 9. The arm 13 is urged in an anti-clock-wise direction by a spring 14 so that the knife 5 normally lies over the concave surface of the shoe 6 and under the leading edge of the lowermost document of the stack 1. The knife 5 may be retracted to a position clear of the leading edge of the document by operation of an electromagnet 15 which attracts a bar 16 of magnetic material carried on the arm 13 and causes the arm 13 to pivot in a clock-wise direction about the shaft 9. A suction source 38 is connected through a flexible pipe 17 to the duct 7 of the shoe 6 and is also connected to the interior of the drum 4 by means not shown. A plurality of grooves 27 are formed in the outer surface of the drum and a plurality of apertures 28 in the circumferential wall connect the interior of the drum with the grooves.

As will be described in detail hereafter the leading edge of a document to be fed is allowed to be attracted towards the outer surface of the drum 4 and the suction applied to the interior of the drum 4 is then effective to produce through the apertures 28 and grooves 27 sufficient frictional engagement to feed the document as the drum 4 is rotated in the direction of arrow 29 (FIG. 2). Document guides 30 are provided around the drum and-an out-feed bed 18 is also provided at a point beneath the drum 4 extending tangentially away from the drum surface. A baffle plate 39 is provided within' the drum 4 opposite the bed 18 so that the suction feeding force is broken at this point to enable documents fed by the drum to leave its surface. Pinch rollers 19 are also provided at the entrance to the bed 18 and these rollers have conventional resilient surfaces to provide frictional engagement of documents with the drum surface at point. It will be realized that conventional feeding means such as pairs of feed rollers are provided in association with the bed 18 to carry the documents away from the drum 4.

In order to feed documents sequentially from the lowermost end of the stack 1 the apparatus is operated in the following manner. The electromagnet 15 is operated to retract the knife 5 thereby permitting the leading edge of the lowermost document to be moved by suction into substantial engagement with the upper surface of the depression 25 in the shoe6. Due to the concave form of this depression 25 this lowermost document is partially deformed at its leading edge, thus tending to ensure that the separation from the stack 1 is confined to only a single document. The electromagnet 15 is then deenergized and the spring 14 causes the knife 5 to return to its normal position so that it enters between the now deformed and separated portion of the leading edge of the lowermost document and the remainder of the stack. Thus, at this stage of the operation of the apparatus, a portion of the leading edge of the lowermost document of the stack is separated from the remainder of the documents in the stack 1 by the knife 5 and is held in a position spaced from the vacuum drum 4 by the shoe 6 In the present apparatus it is preferred that the feeding of documents is regulated on an on-demand" basis and a demand signal is generated by conventional control unit 40 in the event that a document is required to be fed. On receipt of this demand signal the shoe 6 is retracted, leaving the leading edge of the lowermost document unsupported so that the vacuum drum 4 is now effective to attract the document into frictional engagement with the peripheral surface of the drum by differential air pressure in the conventional manner. Rotation of the drum by conventional means (not shown) in the direction of arrow 29 (FIG. 2) is then effective to cause the lowermost document to be drawn from beneath the remainder of the stack and fed around the drum to the fed bed 18.

Under some circumstances particularly when thicker documents are to be fed it may be found that when the leading edge of the document is in engagement with the drum the tractive force obtained by the vacuum acting on this relatively small part of the document may be insufficient to overcome the static frictional forces due to the weight of the remainder of the documents acting on that part of the lowermost document which is supported by the table 2. Under such circumstances or in order to ensure that under all normal operating conditions there is sufficient tractive force at this stage of feeding of the document additional pinch rolls may be provided immediately down stream of the shoe 6. Preferably these additional pinch rolls are made selectively positionable at retracted and operative positions. Thus, in the retracted position these pinch rolls are spaced away from the vacuum drum 4 so that the leading edge of the document is not obstructed during its movement into engagement with the surface of the drum 4. When the leading edge of the document engages the vacuum drum 4 the pinch rolls are then moved into their operative position in which they are resiliently urged toward the drum to cause more positive engagement between the drum and the document.

It will also be appreciated that when employed in an on-demand" mode of operation the drive to the drum 4 preferably includes a clutch mechanism whereby the drum is rotated intermittently. Hence the drive would normally be disengaged and the drum stationary. When the demand signal referred to earlier for initiating feeding of the document is received not only is the shoe 6 retracted to release the document leading edge but the drive to the drum 4 is engaged after the leading edge of the document has moved into engagement with drum surface. This method of control of movement of the drum 4 has the advantage that accurate timing of the document in relation to other utilizing apparatus is improved.

A further refinement which may be made in the structure of the knife 5 is shown in greater detail in FIG. 2. In order to ensure that only a single document is separated from the stack by a shoe 6 a sensing device is provided in association with the knife 5 to determine the thickness of document separated from the stack. The sensing device includes a sensing finger pivotally mounted at 21 on the arm 13 such that an edge 22 at the free end of the finger 20 is able to engage the upper surface of the depression of the shoe 6 when the shoe 6 and the knife 5 are in their normal positions. A spring 31 urges the edge 22 against the shoe 6. Thus after a document end has been attracted into engagement with the concave surface of the shoe 6 with the knife 5 retracted movement of the knife 5 into its normal position causes the edge 22 to slideover the upper surface of the separated document and it will be clear that edge 22 will be separated from the surface of the depression 25 by adistance equal to the total thickness of documents separated from the stack and retained on the shoe 6. The finger 20 carries ablock 23 of magnetic material which constitutes part of a magnetic core of an inductor 24.

The magnitude of the inductance of the inductor 24 is determined by the length of air gap between the block 23 and the remainder of the magnetic core and the length of this air gap is determined by the position of the edge 22 of the finger 20 and hence by the thickness of document retained by the shoe 6. The inductor 24 is connected as part of the circuit of an oscillator which is controlled by the variation of inductance to indicate the thickness of the separated document. Thus after the knife 5 is retracted to allow the leading edge of a document to be attracted on to the shoe 6, the output of the oscillator is examined to determine whether a single document has been attracted or whether no documents or more than one document has been attracted. If a single document indication is obtained the remainder of the document feeding operation is permitted to take place. However, if a signal indicating that more than one document has been separated is obtained, the knife 5 is once more retracted and returned to its normal position again in an attempt to separate a single document from the stack. This operatio n may be repeated a number of times after WhlCh a signal indicating the need for intervention of an operator is generated.

It will be appreciated that the use of this further refinement described above in which a document is partially separated from the stack and a check is made to determine whether correct separation has been effected prior to any feeding of the document away from the stack not'only permits further attempts to be made automatically by the apparatus to separate a single document but also if operator intervention becomes necessary the document which caused mal-operation of the separator is easily identified and removed from the apparatus since it is still in the stack of documents on the table 2. In many instances the fault may be cleared merely by manually removing the stack and replacing it on the table '2..S uch removal and replacement often being sufficient to break the adherence of adjacent documents.

We claim:

1. Document feeding apparatus including stack means to support a stack of documents; separator means to separate and to move a portion of an outer document of the stack away from the remaining documents in the stack to'form a space therebetween; sensing means responsive to the thickness of document moved away from the stack; a knife movable into the space formed between the portion of document moved away from the stack and the remainder of the documents in the stack to retain said portion away from the stack and means responsive to the sensing means sensing a thickness of separated document which differs from the thickness of a single document to withdraw the knife from and move the knife into said space to assist the separator means to separate the portion of only the outermost document from the remaining documents of the stack.

2. Apparatus as claimed in claim lin which the separator means includes a suction source; a document engaging shoe connected to the suction source, the shoe being effective to deform the portion to form the space.

3. Apparatus as claimed in claim 1 in which the separator means is movable between an operative position in which it is efiective to move the portion away from the stack and a withdrawn position in which the portion is free to move further from the stack and feeding means effective when the separator means is in its withdrawn position to remove the separated document from the stack.

4. Apparatus as claimed in claim 3 in which the separator means is movable in the plane of the document to be separated from the stack.

5. Apparatus as claimed in claim 1 in which electromagnetic means are connected to the separator means and to the knife, the electromagnetic means being selectively operable to operate the selector means and the knife to separate the portion of only the outermost document. 

1. Document feeding apparatus including stack means to support a stack of documents; separator means to separate and to move a portion of an outer document of the stack away from the remaining documents in the stack to form a space therebetween; sensing means responsive to the thickness of document moved away from the stack; a knife movable into the space formed between the portion of document moved away from the stack and the remainder of the documents in the stack to retain said portion away from the stack and means responsive to the sensing means sensing a thickness of separated document which differs from the thickness of a single document to withdraw the knife from and move the knife into said space to assist the separator means to separate the portion of only the outermost document from the remaining documents of the stack.
 2. Apparatus as claimed in claim 1 in which the separator means includes a suction source; a document engaging shoe connected to the suction source, the shoe being effective to deform the portion to form the space.
 3. Apparatus as claimed in claim 1 in which the separator means is movable between an operative position in which it is effective to move the portion away from the stack and a withdrawn position in which the portion is freE to move further from the stack and feeding means effective when the separator means is in its withdrawn position to remove the separated document from the stack.
 4. Apparatus as claimed in claim 3 in which the separator means is movable in the plane of the document to be separated from the stack.
 5. Apparatus as claimed in claim 1 in which electromagnetic means are connected to the separator means and to the knife, the electromagnetic means being selectively operable to operate the selector means and the knife to separate the portion of only the outermost document. 